If you've ever flown out of an icy region, you've sat inside the plane while the ground crew sprays the exterior with that orange or green fluid. That de-icing solution removes ice and frost from the wings, allowing the plane to safely take off.

Image: Alex Pereslavtsev, GFDL 1.2

But what happens once the plane is in the air? The wings can continue to collect moisture, particularly as it flies through clouds in sub-freezing temperatures. As ice builds up on the wing, it disrupts the airflow over it, reducing lift and increasing drag. Obviously this is not good.

Thus airplane design teams have devised in-flight anti-icing measures. Just as your car uses the engine's heat to warm the cabin, airplanes use the high temperatures generated by the aircraft's engine to rout hot air across the leading edges of the wings.

Problem solved—as long as the airplane is powered by heat-generating turbine engines. But the future of flight is moving towards alternative propulsion systems, like electric, hybrid-electric and even hydrogen. These systems don't generate the amounts of heat required to de-ice a wing in flight.

Thus the Fraunhofer Institutes, a network of European research institutes, are working on a new method. The Fraunhofer Clean Aviation project sees airplane wings embedded with piezoelectric actuators. These actuators each turn a small amount of electricity into low-frequency vibrations. Sensors on the wing tell the actuators how much to vibrate, and then they shake the ice off, similar in concept to a dog ridding itself of water after a bath.

Notably, the actuators use far less electricity than would, say, heating elements embedded in the wing.

The researchers have proven this method in testing, though not yet in real-world conditions.

"Our experiments in the icing wind tunnel showed that electromechanical deicing works," says researcher Denis Becker. "As the next step, we will be conducting further tests in the wind tunnel to get the system ready for in-flight testing."